21025000109 has 2 divisors, whose sum is σ = 21025000110. Its totient is φ = 21025000108.

The previous prime is 21025000091. The next prime is 21025000127. The reversal of 21025000109 is 90100052012.

Together with previous prime (21025000091) it forms an Ormiston pair, because they use the same digits, order apart.

It is a balanced prime because it is at equal distance from previous prime (21025000091) and next prime (21025000127).

It can be written as a sum of positive squares in only one way, i.e., 20966171209 + 58828900 = 144797^2 + 7670^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21025000109 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21025900109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10512500054 + 10512500055.

It is an arithmetic number, because the mean of its divisors is an integer number (10512500055).

Almost surely, 2^21025000109 is an apocalyptic number.

It is an amenable number.

21025000109 is a deficient number, since it is larger than the sum of its proper divisors (1).

21025000109 is an equidigital number, since it uses as much as digits as its factorization.

21025000109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 180, while the sum is 20.

The spelling of 21025000109 in words is "twenty-one billion, twenty-five million, one hundred nine", and thus it is an aban number.